- This would allow us to recollect our PageRank instead of having it spread among all the possible combinations of writing an URL for a particular page.
- It help SEO to index our content and use a heuristic to find a canonical, so it recommend to specify existent URLs as canonicals.
Ex: <link rel="canonical" href="http://www.mywebsite.com/product/swedish-fish/" />
See: http://googlewebmastercentral.blogspot.com/2009/02/specify-your-canonical.html